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Advisory details: vulnrichment / CVE-2026-55574
Advisory ID vulnrichment/CVE-2026-55574
Aliases
Summary vLLM is a high-throughput and memory-efficient inference and serving engine for LLMs. Prior to 0.24.0, the structured_outputs.regex API parameter passes a user-supplied regular expression string directly to the grammar compiler backends with no compilation timeout; in the xgrammar backend the string reaches the regex compiler with no guard, and in the outlines backend the validation step blocks structural issues such as lookarounds and backreferences but performs no complexity analysis, so a pattern with nested quantifiers passes all checks and causes exponential state-space expansion, allowing a single request containing an adversarial regex to hang an inference worker indefinitely and deny service. This issue is fixed in version 0.24.0.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (1)
CWE-1333 Inefficient Regular Expression Complexity
System Score Found at
cvssv4 8.7
ssvc Track
Reference id Reference type URL
https://github.com/vllm-project/vllm/commit/2b3006076c5e9bc4cda9e03e3641388de3c5c286
https://github.com/vllm-project/vllm/pull/45118
https://github.com/vllm-project/vllm/security/advisories/GHSA-rwxx-mrjm-wc2m
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at None
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

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present

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passive

active

high

low

none

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low

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low

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Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-07-06T20:52:49Z/ Found at None

Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-07-06T20:52:49Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/55xxx/CVE-2026-55574.json

Source Advisory: vulnrichment/CVE-2026-55574

View SSVC decision tree 
[{'Exploitation': 'none'},
 {'Automatable': 'no'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]